Auto merge of #9349 - Alexendoo:format-args-expn, r=flip1995

Refactor `FormatArgsExpn`

It now for each format argument `{..}` has:
- The `Expr` it points to, and how it does so (named/named inline/numbered/implicit)
- The parsed `FormatSpec` (format trait/fill/align/etc., the precision/width and any value they point to)
- Many spans

The caller no longer needs to pair up arguments to their value, or separately interpret the `specs` `Expr`s when it isn't `None`

The gist is that it combines the result of [`rustc_parse_format::Parser`](https://doc.rust-lang.org/nightly/nightly-rustc/rustc_parse_format/struct.Parser.html) with the macro expansion itself

This unfortunately makes the code a bit longer, however we need to use both as neither have all the information we're after. `rustc_parse_format` doesn't have the information to resolve named arguments to their values. The macro expansion doesn't contain whether the positions are implicit/numbered/named, or the spans for format arguments

Wanted by #9233 and #8518 to be able to port the changes from #9040

Also fixes #8643, previously the format args seem to have been paired up with the wrong values somehow

changelog: [`format_in_format_args`]: Fix false positive due to misattributed arguments

r? `@flip1995`
cc `@nyurik`

0 files changed, 0 insertions, 0 deletions